User devices perform an increasing variety of tasks that allow users to make and receive calls and/or access services (e.g., to send and receive messages, download and play audio and/or video content, make electronic purchases, communicate via social networking, etc.) via a network, such as the Internet. The user devices usually provide, to the network, login credentials (e.g., usernames, passwords, personal identification numbers (PINs), etc.), associated with the users, that enable the users to be authenticated prior to being granted access to the services.